Thermostats?

[VileZambonie]

Set the timing to spec. If you are running 87 octane and it's pinging get some top engine cleaner and get rid of the carbon. Make sure you are not running a hotter than stock plug. Is your EGR functioning?

[197]

Could be.  It's just an idea.  Doesn't hurt to try it.   When driving uphill or under a load, does the engine seem to "rattle" some from the valves?  Having 93 octane will disguise this somewhat.  To test this, I'd use 87 octane.  If it rattles some, I'd do as mentioned, retard the timing some.

And it would get a little hot when It was just idling at lights

You mentioned that at idle, it tends to get hot or overheat?  I'd check your clutch fan (if that is what you have) or flush the radiator.  How old is your water pump?  If your cooling system is not decipating the heat correctly, it will remain in the engine and contribute to diesling due to the heat. 

No rattle under load or uphills.

And for the temp, when idling it will go up alittle but it wont get to hot and its never overheated.

What do you suggest for a topend cleaner?

Also we retimed it last spring when we replaced the cap,rotor,wires,plug,carb... and I beleve its a 9 or 10.

Whats a EGR?

[Lt.Del]

[197]

Whats the egr do?

[okuma]

I USED TO HAVE A 305 ON A CAPRICE CLASSIC. I WOULD ALWAYS PUT 93 OCTANE, BUT WHEN $ CRISIS CAME I WOULD ONLY PUT CHEAP 83 OCTANE. I GUESS THE CARB. GOT USED TO GOOD GAS, BECAUSE I DID EVERYTHING TO IT AND IT WOULD STILL RATTLE AND STAY ON A FEW SECONDS  AFTER I WOULD TURN IT OFF!

[VileZambonie]

EGR = Exhaust Gas Recirculation. It take inert gas (exhaust gas) and redirects it into the combustion chamber to reduce the temperatures of combustion effectively lowering oxides of nitrogen (NOx). NOx is produced when combustion temperatures exceed 2500°F